STPMS1

Application

Doc ID 16524 Rev 2

9/23

5

Application

The choice of external components in the transduction section of the application is a crucial

point in the application design, affecting the precision and the resolution of the whole

system.

Among the several considerations, a compromise must be found between the following

needs:

1.

Maximize the signal to noise ratio in the voltage and current channel

2.

Choose the current to voltage conversion ratio Ks and the voltage divider ratio in a way

that calibration can be achieved (see also the AN2299; Fast digital calibration

procedure for STPM01 based energy meters, application note)

3.

Choose Ks to take advantage of the whole current dynamic range according to desired

maximum current and resolution.

To maximize the signal to noise ratio of the current channel the voltage divider resistors ratio

should be as close as possible to that shown in Table 6.

Figure 4 below shows a reference schematic for an application with the following properties:

●

P = 64000 imp/kWh

●

INOM = 5 A

●

IMAX = 60 A

Typical values for the current sensors sensitivity are indicated in Table 6.

Figure 4.

Timing diagram

AM07833v1

AM07833v1